While I probably will try out the co-op at some point, I'd rather complete the trilogy in SP mode first with the characters I have.

I tried the co-op in the demo (solo) and found the character seems to 'stick' to cover too well at times; trying to get it to break cover didn't work smoothly at times. And you have to move, since you can't camp at all without the AI attacking you or throwing grenades at your position very accurately.

Same, I want to go through the campaign for the most part. I at some point want to do the co-op to help it unlock whatever the hell it does in single player.